import java.util.*;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int[] w = new int[N];
    for(int i = 0; i < N; i++) w[i] = sc.nextInt();
    // dp[i][j]は重りiまでで和をj-10000と出来るかを表す
    int[][] dp = new int[N][20001];
    dp[0][w[0] + 10000] = 1;
    dp[0][-w[0] + 10000] = 1;
    for(int i = 1; i < N; i++) {
      for(int j = 0; j < 20001; j++) {
        if((dp[i - 1][j - w[i]] == 1) || (dp[i - 1][j + w[i]] == 1)) dp[i][j] = 1;
      }
    }
    String ans = "impossible";
    if(dp[N - 1][0] == 1) ans = "possible";
    System.out.println(ans);
  }
}